(1) Field of the Invention
The present invention relates generally to a dial indicator, and more particularly relates to a dial indicator capable of providing both local visible indication and remote indication of a physical parameter.
(2) Background Information
Dial indicators (also variously referred to as dial gauges, indicator gauges, dial faces, and/or analog gauges) are commonly used to indicate a host of physical parameters such as temperature, pressure, electrical properties, liquid levels, among others. For example, liquid storage tanks for fuel, oil, propane, natural gas, and ammonia typically include a dial indicator attached thereto for providing an on-site, visible reading of the liquid level (i.e., the percentage of the total tank volume occupied by the liquid. For many applications it is desirable, both for convenience and economic factors, to have both local visible indication and remote indication of the above-mentioned physical parameters. For example, it is generally necessary for a user to be aware of the quantity of remaining liquid in a liquid storage tank, such as for determining when refilling is necessary. In some industrial applications, in which large numbers of tanks are employed, remote indication may be desirable. However, local visual indication may also be desirable, for example, to monitor the filling operation.
Examples of indicators providing both on-site and remote indication are disclosed in U.S. Pat. No. 4,554,494 to Howeth; U.S. Pat. No. 4,911,011 to Fekete, et al.; U.S. Pat. No. 4,975,687 to Murphy, Jr. et al.; U.S. Pat. No. 4,987,400 to Fekete; U.S. Pat. No. 5,305,639 to Pontefract; and U.S. Pat. No. 5,357,815 to Williamson; each of which is fully incorporated by reference herein. Fekete, et al., in U.S. Pat. Nos. 4,911,011 and 4,987,400, for example, disclose a dial indicator having a magnetically driven voltage divider built into the device behind the dial face for providing an electrical indication of liquid level in a liquid storage tank.
The above systems tend to be complex and therefore may be relatively expensive. Further, for some applications for which both local and remote indication are desirable, it may not be economically feasible to replace the existing gauge. Further still, for many applications, dial indicators providing for both local visual and remote indication may not be commercially available. Therefore, there exists a need for a relatively simple and inexpensive dial indicator that provides for both onsite and remote indication. There also exists a need for a relatively simple and inexpensive method for upgrading a conventional dial indicator (which provides only visual indication) to include the capability of providing remote indication.
One aspect of the present invention includes a method for upgrading a dial indicator to provide both local visible and remote indication of a physical parameter. The method includes providing the dial indicator with a magnetic rotary pointer, the magnet rotary pointer being rotatable in response a change in the physical parameter. The method further includes magnetically coupling a potentiometer to the magnet, the potentiometer being magnetically adjustable, wherein a rotation of the magnet causes a change in the electrical output of the potentiometer and fastening said potentiometer to a front side of the dial indicator. In variations of this aspect, the magnetic rotary pointer is provided by securing a magnet to a pre-existing rotary pointer, or by replacing the pre-existing rotary pointer with a replacement rotary pointer having a magnet integrated therewith. In another variation of this aspect the dial indicator is mounted to a liquid storage tank and the potentiometer is fastened to the dial indicator by interposing it between a transparent bracket and a transparent cover, and fastening the bracket to the dial indicator.
In another aspect, this invention includes a kit for upgrading a dial indicator to provide both local visible and remote indication of a physical parameter. The kit includes a magnet, sized and shaped for coupling to the dial indicator in a manner in which the magnet rotates in response to a change in the measured physical parameter, a magnetically adjustable potentiometer, and a mounting assembly that includes a bracket, sized and shaped for fastening the potentiometer to the dial indicator. In variations of this aspect, the magnet may be sized and shaped for being secured to a pre-existing rotary pointer of the dial indicator, or the magnet may include a replacement rotary pointer.
In yet another aspect, this invention includes a dial indicator for providing a local visible and a remote display of a liquid level in a liquid storage tank. The dial indicator includes a magnetic rotary pointer which is rotatable in response to a change in the liquid level in the tank. The dial indicator further includes a magnetically adjustable potentiometer including a voltage divider and at least two electrical connectors, the potentiometer being magnetically coupled to the magnetic rotary pointer so that rotation of the magnetic rotary pointer causes a change in the electrical output of the potentiometer. The potentiometer is mounted to a front side of the dial indicator by a transparent bracket. In variations of this embodiment, the magnetic rotary pointer includes a rotary pointer having a magnet secured thereto, or includes a replacement rotary pointer having a magnet disposed integrally therewith.